Katt's guide to AC wiring color codes!
Green: should be safe to lick.
White: might be safe, but inadvisable.
Black, Red, Blue: do not lick
Brown, Orange, Yellow: most definitely do not lick.
OH and this only applies to the US. Other lickability standards exist in different countries.
Katt talks about wiring phases
So I feel like going on about this since I think it's cool.
Residential wiring is what's called split-phase. You have an A phase (default black) and a B phase (default red) that are 120V (RMS) AC sine waves and 180 degrees out of phase with each other. The voltage between the two phases is 240V (useful for things like heaters and large appliances). Neutral (white) is held to zero volts and serves as current return for both phases.
Katt talks about wiring phases
IMPORTANT PROGRAMMING NOTE: if you have a device that only needs 240V, it will often be run on a two-conductor wire that only has black and white wires inside. This means that the white, which is normally neutral, is actually a 120V hot.
This SHOULD be marked with black tape or a marker, but isn't always.
Katt talks about wiring phases
In industrial settings you'll also see 480V three-phase power. That's the brown, orange, and yellow hots (aka "BOY colors").
Hot to neutral is 277V and hot-to-hot is 480V.
I haven't worked with this yet.
Katt talks about wiring phases
AC power voltage isn't measured zero-to-peak! The peak voltage of a "120V" sine wave is actually 170V.
120V is the "RMS" (root mean square) voltage.
"For alternating electric current, RMS is equal to the value of the direct current that would produce the same average power dissipation in a resistive load."
Katt talks about wiring phases
@starkatt We use that as input to our lab's power supply.
Far beyond our level is 13.8 kV, usually called thirteen-eight. That's the line-to-line voltage; line-to-neutral is 8 kV. That's the level they use on really high-power industrial stuff, like the motors that drive a paper mill.
Katt talks about wiring phases
Commercial wiring is different!
There's black, red, and blue phases! Each of them is 120V AC, but there 120 degrees out of phase instead of 180. This means the voltage between any two phases is 208V. You can run three different hot phases all sharing one neutral, and if the loads are balanced then the neutral isn't actually carrying any current. You can also plug three-phase power directly into a three-phase AC motor.